This invention relates to a system for withdrawing water from a container such as a hot tub or swimming pool, forcing the water to separate into two paths, treating the water in one path differently from the way the water in the other path is treated, and returning the treated water from both paths to the container. In particular, the invention pertains to such a system in which the water moving along one of the paths passes through a filter to remove certain contaminants and the water moving along the other path goes through a venturi that has a side opening through which a gas containing ozone is supplied to that water. After passing through the venturi, the water in the latter path passes through a water line of sufficient length to hold the bubbles entrained in the water a sufficient time to allow the ozone in the gas to permeate into the water before the water returns to the container.
Systems for treating water from a hot tub normally withdraw the water through one or more drains in the bottom and side of the tub into a loop which includes a pump that moves the water, and a filter which removes some contaminants from the water. It is also common practice to include a heater in the loop between the filter and the nozzle or nozzles and through which the water passes as it returns to the tub. People using hot tubs also like to have bubbles included in the water that reenters the tub, and this can be accomplished by forcing the water through a venturi that has a side port through which air can be drawn into the stream of water by the reduced pressure in the venturi.
As a further improvement in the treatment system, instead of plain air, a source of gas that includes ozone may be connected to the port. The gas may be air with part of its oxygen converted into ozone. Ozone has a very beneficial effect in purifying the water. Some of this effect is due to chemical transformation of some of the contaminants into a form suitable to be captured by the filter. However, in order to act chemically on the contaminants, the ozone, which enters the stream of water as part of the gas in bubbles, must permeate the wall of water that surrounds and defines each bubble. Fortunately, ozone does permeate into the water more easily than do other components of air (the gas normally used in such treatment systems), but the permeation takes a little while, and the bubbles must not be able to reach the water-air interface at the surface of the water in the container before the permeation is at least substantially complete. In order to be sure that the bubbles are retained long enough, the venturi is separated from the container by a water line several feet long.
It is not always easy or even possible to arrange all of the required components, including water line lengths, in the required relationship in sequence and to keep all of them operating in an optimum or even satisfactory manner.